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A series of pentasubstituted 4H-pyrans and tetrahydrobenzo[b]pyrans are synthesized with excellent yields via a one-pot condensation of aromatic aldehydes, malononitrile, and a dicarbonyl compound, ethyl acetoacetate, acetyl-acetone or dimedone, in the presence of 4 Å molecular sieve modified with zinc(II) as heterogeneous catalyst, in ethanol. The process offers numerous advantages, such as better yield, short reaction time, and mild reaction conditions. The catalyst's preparation is simpledoi:10.1515/gps-2017-0083 fatcat:dvt6tyekindk3pxz3basyqsl5q